Not Applicable.
The invention of this application is described as applied to motorized conveyor pulleys, but it has application to dead shaft pulleys (those in which the shaft of a pulley is fixed against rotation, the drum of the pulley being mounted on bearings to rotate about the shaft) generally as well. Motorized conveyor pulleys have an electric motor inside a drum of the pulley, and a shaft with extensions at each end, fixed against rotation in mounting blocks mounted on a conveyer frame. Conveyer frames are welded structures that inherently do not have the positional accuracy required to mount machine components. Machining the frame structure to create a proper alignment is expensive and many conveyor structures are too large to be machined. In a motorized conveyor pulley a rigid mounting of the pulley in misalignment will cause excessive stress and lead to early failure of either the pulley or the frame. Thus, there must be some provision for aligning the shaft extensions and mounting blocks when the pulley is installed.
Conventionally, the shaft extensions of a motorized conveyor pulley are loosely fitted in mounting blocks in the form of yokes to allow for misalignment. Such a loose fit is noisy and leads to wear due to relative motion and impact loading. This is likely to cause early failure. For food and beverage service, the gap between the shaft and the mounting block can trap food.
One of the objects of this invention is to provide a mounting structure for a motorized conveyor pulley that accommodates misalignment but at the same time minimizes noise and relative motion, and provides a more sanitary arrangement for food and beverage service installations.
Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawings.
In accordance with this invention, generally stated, a mounting for a dead shaft or motorized conveyor pulley is provided in which the shaft of the pulley is mounted at least one end in a pivot sphere, the sphere being mounted in a complementarily socketed block against rotation around the axis of rotation of the shaft when pulley is in use, but to permit angular movement in response to misalignment of the shaft from one end of the drum to another end during its installation. In a motorized pulley, the shaft is a composite, with shaft extensions extending from both ends of a pulley drum. Inasmuch as the extensions are part of the shaft as a whole, they are encompassed within the term xe2x80x9cshaftxe2x80x9d as used herein, when referring to the shaft""s projecting from the drum. Preferably, each of the shaft extensions is mounted in a sphere against rotation. In both the dead shaft and motorized pulleys, the sphere is held against rotation around the axis of the shaft by clamping of the mounting block around the sphere. A positive restraint as a back-up can be provided in the form of a pin extending from the mounting block into a slot in the exterior of the sphere parallel to the axis of rotation of the pulley.